Radio Society of Great Britain
High Wycombe - Winner's Blog

I elected to do the four transmitter course which comprised TXs 1,3,4,5. I had offered to accompany Martin M0NXP on his first DF hunt. He started 5 minutes before me and spent the extra five minutes getting to grips with the receiver and taking a few bearings until I joined him. From the start I chose to stay as high as I could beside the fence that led towards the wood and from there I got a set of bearings on the four transmitters. As Steve noted in his comments TX 1 showed up to the west but with hindsight, I should have been less trusting of it since it was not strong and the edge of the map was only 450 metres away!. With the benefit of 20/20 hindsight I can now see how the signal from TX1 was screened directly from the start but was channelled up the big re-entrant that deepened as it ran southwards from the start. Due to a curve in the line of this re-entrant the signal from TX 1 was reflected from the woods opposite the start to come in from a westerly direction.
I got TXs 1 and 5 to the west and 3 and 4 to the south. 3 was louder than 4 and the bearing was less diffuse than 4 and along the line of the fence. On that basis I chose to go 3-4-1/5 and duly set off for TX 3.
The bearing was pretty much due south and crossed from one side of the big re-entrant to the other. Slightly reluctantly I lost all my height as I headed off for the gate into the wood, ran down the re-entrant for a bit before peeling off right to climb the western side diagonally, vaguely along the line of the path shown on the map which I never did identify on the ground. Soon after I started climbing TX3 came on again, the bearing was rather more diffuse now, indicating that it was not line of sight. As it went off the air, range estimation gave 200m (i.e., 100 - 400m away) so I carried on along the same line for about this distance and stopped on a slight rise on the hillside to await its reappearance. When it fired up it was to the right, at right angles to the track taken up the hill - the range estimation had been spot on. Charging off along the bearing soon brought the edge of the wood in sight and some likely looking holly bushes. Just as it went QRT Martin and I arrived to find it behind a holly bush.

In the confusion of getting in and out of the holly and punching, I missed the next transmission from 4 and decided to amble southwards along the fence to the fence corner by the oob area which looked to be an excellent bearing taking location with the ground falling away to the east and south. While I waited I took the opportunity to plot bearings on TX 1 and TX 5. It was now obvious that TX 1 was not west of the start after all but was over towards the SE corner of the map. TX 5 was confirmed as being somewhere west of the start and given the 400m start circle and the edge of the map, TX 5 was now pin pointed in a 100m diameter circle.
TX 4 fired up and I got a rather poor bearing and a range estimation of 200m. The actual distance to TX 4 was 450m and the range estimation was screwed up by the fact that it was on the opposite side of a huge re-entrant and the radio path was totally unobstructed. Believing the range to be rather less than this, Martin and I descended to the floor of the re-entrant to await the next transmission when my plan was to determine whether the TX was on the south or north side of the bottom of the re-entrant. The answer soon came as the south side and another diagonal climb of the side of a re-entrant followed. Martin said he thought the transmitter was getting weaker but I felt this was due to the radio path becoming more obstructed as we were now below the transmitter on a convex slope. We carried on for what seemed a reasonable distance before stopping to await the next transmission. I took the opportunity to get another bearing of TX1 onto the map as we waited.
TX 4 fired up again a bit to the right and it was time to leg it to try to run it down in the 50 seconds or so of the transmission remaining. Just as it went QRT, I spotted a flash of orange behind a tree about 20m away and that got a second transmitter in the bag.

After punching TX4 I took yet another bearing on TX1 and this pinned it down to a 100m diameter circle on a corner of the hillside across the valley. Martin seemed to think it was below us in the same bit of wood as TX4 but this was well inside the 400m minimum distance to the next TX, so we set off for the flog across the valley. As I tottered up the other side I said to Martin 'I'm knackered, you carry on ahead' but he seemed content to stay where he was. TX 1 came on again during this trek but we were nicely in position on the main track on the bend in the hillside when TX 1 fired up again. It was about 60m away and was easily run down during the transmission.
At this point I saw that my choice of transmitter sequence was not optimum. I had been fooled by the poor bearing to TX1 at the start to choose to take the transmitters in a figure of eight route instead of an open loop.

There was a nice fairly flat path leading along the side of the re-entrant from TX1 back towards the start and TX5. Knowing where TX5 was located within about 50m made it easy to get to the edge of the 400m circle west of the start and wait for it to fire up. As soon as it did, the familiar charge down the bearing followed and Martin was the first to spot the TX up by the fence. After that it was hey ho for the finish, most of which was thankfully down hill.

Bob Titterington